Mac Pro - Raid/Bootcamp Help?

I am trying to set up boot camp. I just bought my Mac Pro and it has 3 X 500 GB drives. When I get to the partition option in the bootcamp setup, I am only able to partition part of one of the drives, when I want to dedicate an entire drive to Windows. Do I have to set up a raid array to do this? How do I go about that...Thanks alot